The present invention relates generally to the storage and data networking fields, and more particularly, relates to a method, virtual network adapter and computer program product for automatically maximizing frame sizes and avoiding physical network Internet Protocol (IP) fragmentation.
As used in the present specification and claims, the term virtual network adapter should be understood to include a network adapter that uses a physical link of a physical adapter to transmit and receive frames over an IP based physical network.
Internet protocol (IP) has been defined to provide for transmitting blocks of data called internet datagrams from sources to destinations, where sources and destinations are hosts identified by fixed length addresses. The internet datagram is a unit of data including an internet header exchanged between the source and destination internet computer systems. The internet protocol implements two basic functions of addressing and fragmentation. The internet protocol is specifically limited in scope to provide the functions necessary to deliver a package of bits, the internet datagram, from a source to a destination over an interconnected system of networks.
The internet protocol (IP) provides for fragmentation and reassembly of long datagrams for transmission through small packet networks. If an IP datagram is too large to send as a single frame over a network, IP performs IP fragmentation on the IP datagram. IP uses predetermined fields in the internet protocol header to fragment and reassemble internet datagrams. IP resides in each host engaged in internet communication and shares common rules for interpreting address fields and for fragmenting and assembling internet datagrams.
IP fragmentation on the IP datagram breaks the IP datagram into smaller IP datagrams that can be sent over the network. IP fragmentation uses a fair amount of system resources, especially if a fragment is lost or dropped, and CPU cycles to reassemble an original datagram. It is best to avoid IP fragmentation when maximum performance is desired.
In the context of a virtual network adapter, a need exists for an effective mechanism for automatically maximizing frame sizes, and avoiding physical network Internet Protocol (IP) fragmentation, to provide improved performance.
Principal aspect of the present invention are to provide a method, virtual network adapter and computer program product for automatically maximizing frame sizes and avoiding physical network Internet Protocol (IP) fragmentation. Other important aspects of the present invention are to provide such a method, virtual adapter and computer program product for automatically maximizing frame sizes and avoiding physical network Internet Protocol (IP) fragmentation substantially without negative effect and that overcome many of the disadvantages of prior art arrangements.
In brief, a method, virtual adapter and computer program product are provided for automatically maximizing frame sizes and avoiding physical network Internet Protocol (IP) fragmentation. A maximum frame size of a selected physical adapter is identified. A frame size for a virtual adapter is calculated using the identified maximum frame size of the selected physical adapter. The calculated frame size of the virtual adapter is reported to an operating system.
In accordance with features of the invention, the frame size of the virtual adapter is automatically adjusted to a maximum frame size corresponding to the maximum frame size of the selected physical adapter, so that the largest possible frames are allowed, while avoiding physical network Internet Protocol (IP) fragmentation. A performance benefit or improved performance is enabled using the maximum size frames, rather than a fixed small frame size to avoid physical network Internet Protocol (IP) fragmentation used in some conventional arrangements. The calculated frame size of the virtual adapter includes an adjustment for the header length of the physical network adapter's media access address (MAC) header, an internet protocol (IP) header, and each header and each trailer unique to the virtual adapter implementation.
The present invention together with the above and other objects and advantages may best be understood from the following detailed description of the preferred embodiments of the invention illustrated in the drawings, wherein:
Having reference now to the drawings, in
Computer system 100 is shown in simplified form sufficient for understanding the present invention. The illustrated computer system 100 is not intended to imply architectural or functional limitations. The present invention can be used with various hardware implementations and systems and various other internal hardware devices, for example, multiple main processors. Various commercially available computers can be used for computer system 100, for example, an IBM computer or server system.
Referring now to
It should be understood that the present invention is not limited to the illustrated virtual network adapter system 200. For example, the number N of virtual adapters 208 and the number M of physical adapters 212 are not necessarily the same number. That is, there is not necessarily a one-to-one correspondence for a virtual adapter 208 to a physical adapter 212. For example, all the virtual adapters 1-N, 208 could use the same physical adapter 212.
In accordance with features of the invention, each virtual adapter 208 automatically adjusts its maximum frame size corresponding to the maximum frame size of the selected underlying physical adapter 212. The largest possible frames are allowed for virtual adapters 208, while physical network Internet Protocol (IP) fragmentation is avoided. IP fragmentation can occur when adding required network headers and trailers causes the resultant physical frame to exceed the maximum frame size of the underlying physical adapter 212. The method of the invention enables improved performance by using the maximum size frames, rather than a fixed smaller frame size that are typically used in some conventional arrangements to avoid IP fragmentation.
Referring now to
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A sequence of program instructions or a logical assembly of one or more interrelated modules defined by the recorded program means 404, 406, 408, 410, direct the virtual adapter system 200 for implementing maximum frame size and avoiding physical network Internet Protocol (IP) fragmentation of the preferred embodiment.
While the present invention has been described with reference to the details of the embodiments of the invention shown in the drawing, these details are not intended to limit the scope of the invention as claimed in the appended claims.